Laminate structure and spintronics device

Abstract

To provide a laminate structure of which a Gilbert attenuation α is small, and provide a spintronics device using them.SOLUTION: A laminate structure 1 includes: a support body layer 11; and a thin film formation part 12 formed onto one surface side of the support body layer 11. The thin film formation part 12 contains a construction that an in-surface magnetic film 121 of which a magnetization direction is an in-surface and a vertical magnetization film 122 of which the magnetization direction is vertical to the in-surface are arranged via a non-magnetic body 123. In the thin film formation part 12, it is preferably that the in-surface magnetic film 121 and the vertical magnetization film 122 are laminated via the non-magnetic body 123.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminated structure and a spintronics device. [Background technology]

[0002] In recent years, the field of spintronics (spin+electronics) has been attracting attention as it seeks to realize high-performance devices by utilizing the spin of electrons in electronics. In spintronics devices, magnetic properties are electrically controlled. For example, in the magnetic head of a hard disk drive (HDD), which is an example of a spintronics device, information is stored by passing an electric current through it to reverse the direction of magnetization, and the two states of magnetization, upward and downward, correspond to 0 and 1.

[0003] The prior art Patent Document 1 discloses a magnetic stack having a layered structure in which a free magnetic layer whose magnetization direction is in-plane and a fixed magnetic layer whose magnetization direction is perpendicular to the plane are stacked with a non-magnetic dielectric (MgO) interposed therebetween, and a transmitting device equipped with the magnetic stack. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-520107 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to utilize spin waves, in which the precession of magnetization in a ferromagnetic material dynamically propagates through space, in spintronics devices, the long-distance propagation of spin waves is required. The Landau-Lifshitz-Gilbert equation (hereinafter referred to as the LLG equation) shown in the following Equation 1 is known as an equation that describes the precession of magnetization.

[0006]

number

[0007] In formula 1, M is magnetization, t is time, and H eff : effective magnetic field, γ: gyromagnetic ratio of electrons, α: Gilbert damping constant (sometimes called magnetic damping constant or Gilbert damping constant).

[0008] The LLG equation expresses that the time change of magnetization (left side) is caused by the precession due to the effective magnetic field (first term on the right side) and the relaxation in the direction of the effective magnetic field (second term on the right side). According to this LLG equation, it can be understood that magnetic phenomena are closely related to the relaxation phenomenon of the magnetic moment.

[0009] To realize long-distance propagation of spin waves in spintronics devices, it is important to develop materials and structures with a small Gilbert damping constant α. The smaller the Gilbert damping constant α, the smaller the magnetic friction, which makes it possible to reduce power consumption when electrically controlling magnetic properties.

[0010] The present invention has been made in view of the above problems, and aims to provide a stacked structure having a small Gilbert damping constant α, and a spintronics device using the same. [Means for solving the problem]

[0011] One aspect of the present invention is A support layer; A thin film forming portion is formed on one side of the support layer, The thin film forming section includes: a structure in which an in-plane magnetized film, the magnetization direction of which is in-plane, and a perpendicular magnetized film, the magnetization direction of which is perpendicular to the in-plane, are arranged with a non-magnetic material interposed therebetween; It is in a laminated structure.

[0012] Another aspect of the present invention is A spintronics device having the laminated structure. Effect of the Invention

[0013] The laminated structure has a thin film forming portion including a structure in which an in-plane magnetized film whose magnetization direction is in-plane and a perpendicular magnetized film whose magnetization direction is perpendicular to the in-plane are arranged with a non-magnetic material interposed therebetween, and therefore, the laminated structure has an effect of reducing the Gilbert damping constant α.

[0014] The spintronics device includes the laminated structure, and therefore, the spintronics device has an effect of enabling reduction in power consumption due to the small Gilbert damping constant of the laminated structure. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram that illustrates a schematic example of a laminate structure of a laminated structure according to an embodiment. [Diagram 2] FIG. 2 is an explanatory view that illustrates a schematic diagram of another example of the laminate structure of the laminate structure according to the embodiment. [Diagram 3] FIG. 3(a) shows the XRD pattern of a laminated structure sample when the Co film thickness t = 0.3 nm, and FIG. 3(b) shows the magnetization curve of the laminated structure sample when the Co film thickness t = 0.3 nm. [Figure 4] FIG. 4(a) shows the XRD pattern of a laminated structure sample when the Co film thickness t = 0.4 nm, and FIG. 4(b) shows the magnetization curve of the laminated structure sample when the Co film thickness t = 0.4 nm. [Diagram 5] FIG. 5(a) shows the XRD pattern of a laminated structure sample when the Co film thickness t = 0.5 nm, and FIG. 5(b) shows the magnetization curve of the laminated structure sample when the Co film thickness t = 0.5 nm. [Figure 6]FIG. 6(a) shows the XRD pattern of a laminated structure sample when the Co film thickness t = 0.7 nm, and FIG. 6(b) shows the magnetization curve of the laminated structure sample when the Co film thickness t = 0.7 nm. [Figure 7] FIG. 7(a) shows the XRD pattern of a laminated structure sample when the Co film thickness t = 0.8 nm, and FIG. 7(b) shows the magnetization curve of the laminated structure sample when the Co film thickness t = 0.8 nm. [Figure 8] FIG. 8 is an explanatory diagram of ferromagnetic resonance measurement for a laminated structure sample produced in an experimental example. [Figure 9] FIG. 9 is a diagram showing an example of a resonance absorption spectrum of a laminated structure sample produced in an experimental example. [Figure 10] FIG. 10 is a graph showing an example of resonance absorption at 8.6 GHz in a laminated structure sample produced in an experimental example. [Figure 11] FIG. 11 is a diagram showing an example of the relationship between the resonance frequency fres (GHz) (horizontal axis) and the resonance linewidth ΔH (Oe) (vertical axis) of the resonance absorption spectrum of a laminate structure sample produced in an experimental example. [Figure 12] FIG. 12 is a graph showing the relationship between the resonance frequency fres (GHz) (horizontal axis) and the resonance linewidth ΔH (Oe) (vertical axis) of the resonance absorption spectrum when the thickness t nm of the Co film is changed in an experimental example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Embodiment> The stacked structure and spintronics device according to this embodiment are as follows.

[0017] [1] A support layer; A thin film forming portion is formed on one side of the support layer, The thin film forming section includes: a structure in which an in-plane magnetized film, the magnetization direction of which is in-plane, and a perpendicular magnetized film, the magnetization direction of which is perpendicular to the in-plane, are arranged with a non-magnetic material interposed therebetween; Laminated structure. [2] In the thin film forming portion, the in-plane magnetization film and the perpendicular magnetization film are laminated via the non-magnetic material. The laminated structure according to [1]. [3] The perpendicular magnetic film is composed of a multilayer film in which a plurality of thin films are stacked, or a single layer film made of one thin film. The laminate structure according to [1] or [2]. [4] the perpendicular magnetic film is composed of a multilayer film in which a lamination unit, in which a second ferromagnetic film different from the first ferromagnetic film is laminated on one surface of a first ferromagnetic film, is laminated for one period or more. The laminated structure according to any one of [1] to [3]. [5] the thickness of either the first ferromagnetic film or the second ferromagnetic film is adjusted so that the magnetization direction of the perpendicular magnetization film is perpendicular to the in-plane direction throughout the film; The laminated structure according to [4]. [6] the perpendicular magnetic film has a repeating structure in which ferromagnetic films and non-magnetic films are alternately laminated; The laminated structure according to any one of [1] to [3]. [7] A spintronics device having a stacked structure according to any one of [1] to [6].

[0018] The laminated structure described in [1] above has a thin film forming portion including a structure in which an in-plane magnetized film whose magnetization direction is in-plane and a perpendicular magnetized film whose magnetization direction is perpendicular to the in-plane are arranged via a non-magnetic material. Therefore, the laminated structure described in [1] above has the effect of reducing the Gilbert damping constant α.

[0019] In the laminated structure described in [2] above, the in-plane magnetization film and the perpendicular magnetization film are laminated with a non-magnetic material interposed therebetween. Therefore, in addition to the effects of the laminated structure described in [1] above, the laminated structure described in [2] above has the effect of making it possible to reduce the size of the laminated structure compared to the case where the in-plane magnetization film and the perpendicular magnetization film are arranged in a plane with a non-magnetic material interposed therebetween.

[0020] In the laminated structure described in [3] above, the perpendicular magnetic film is composed of a multilayer film or a single layer film. When the perpendicular magnetic film is composed of a multilayer film in the laminated structure described in [3] above, the thicknesses of the laminated thin films can be variously combined, so that the degree of freedom when making the magnetization direction perpendicular to the in-plane of the film as a whole can be increased. In addition, this improvement in the degree of freedom also provides controllability of the Gilbert damping constant α. On the other hand, when the perpendicular magnetic film is composed of a single layer film in the laminated structure described in [3] above, the number of film formations can be reduced when forming the perpendicular magnetic film, so that the manufacturability of the laminated structure can be improved. In addition, the thickness of the magnetic thin film in the laminated structure can be reduced, so that the power consumption required for controlling magnetism can be reduced.

[0021] In the laminated structure described in [4] above, the perpendicular magnetic film is composed of a multilayer film in which a laminate unit, in which a second ferromagnetic film is laminated on one surface of a first ferromagnetic film, is laminated for one period or more. Therefore, the laminated structure described in [4] above has the effect of the laminated structure described in any one of [1] to [3] above, and further has the effect that the magnetization direction of the entire film can be made perpendicular to the in-plane by adjusting the thickness of at least one of the laminated first ferromagnetic film and second ferromagnetic film.

[0022] In the laminated structure described in [5] above, the thickness of either the first ferromagnetic film or the second ferromagnetic film is adjusted so that the magnetization direction of the perpendicular magnetic film is perpendicular to the in-plane direction throughout the film. Therefore, in addition to the effects of the laminated structure described in [4] above, the laminated structure described in [5] above has the effect of simplifying the film formation process of the perpendicular magnetic film, thereby improving the manufacturability of the laminated structure.

[0023] In the laminated structure described in [6] above, the perpendicular magnetic film has a repeating structure in which ferromagnetic films and non-magnetic films are alternately and repeatedly laminated. Therefore, the laminated structure described in [6] above has the effect of reducing magnetization in addition to the effect of the laminated structure described in any one of [1] to [3] above.

[0024] The spintronics device described in [7] above has the stacked structure described in any one of [1] to [6] above. Therefore, according to the spintronics device described in [7] above, since the Gilbert damping constant of the stacked structure is small, it is possible to reduce power consumption.

[0025] Hereinafter, the stacked structure and the spintronics device of the present embodiment will be described in detail with reference to the drawings.

[0026] (Laminated structure) 1 and 2, the laminated structure 1 of this embodiment has a support layer 11 and a thin film forming portion 12. The support layer 11 is a layer that serves as a reference for crystal growth when forming a thin film, and serves as a substrate that supports the formed thin film.

[0027] The thin film forming portion 12 is formed on one side of the support layer 11. It is sufficient that the thin film forming portion 12 is formed on at least one side of the support layer 11, and as exemplified in Figures 1 and 2, it may be formed on only one side of the support layer 11, or, although not shown, it may be formed on both sides of the support layer 11. The laminated structure 1 refers to one in which one or more thin films are laminated on at least one side of the support layer 11.

[0028] The thin film forming portion 12 includes an in-plane magnetization film 121, a perpendicular magnetization film 122, and a non-magnetic body 123. The in-plane magnetization film 121 has a magnetization direction in-plane. The in-plane magnetization film 121 may be composed of a single layer film made of one thin film as exemplified in Figs. 1 and 2, or may be composed of a multi-layer film in which a plurality of thin films are stacked, although not shown. When the in-plane magnetization film 121 is composed of a multi-layer film, the in-plane magnetization film 121 is a film in which magnetization is arranged in-plane as a whole film.

[0029] The magnetization direction of the perpendicular magnetization film 122 is perpendicular to the in-plane direction. It can also be said that the magnetization direction of the perpendicular magnetization film 122 is perpendicular to the magnetization direction of the in-plane magnetization film 121. Note that the term "perpendicular" in this disclosure does not only mean that the direction is strictly perpendicular to the in-plane direction geometrically, but also includes the range that is considered to be perpendicular to the in-plane direction (direction perpendicular to the plane) when the magnetization direction is discussed in the magnetic material field. The perpendicular magnetization film 122 may be composed of a multilayer film in which multiple thin films are stacked, as exemplified in FIG. 1 and FIG. 2, or may be composed of a single layer film made of one thin film, although not shown. When the perpendicular magnetization film 122 is composed of a multilayer film, the perpendicular magnetization film 122 is a film in which magnetization is aligned perpendicularly as a whole film.

[0030] The non-magnetic body 123 is intended to block direct magnetic coupling between the in-plane magnetization film 121 and the perpendicular magnetization film 122. The non-magnetic body 123 is made of a non-magnetic material. The non-magnetic body 123 can be preferably made of a non-magnetic metal material (including alloys, omitted below). The non-magnetic body 123 can usually be formed in the form of a film. The non-magnetic body 123 may be made of a single layer, as exemplified in Figs. 1 and 2, or may be made of multiple layers, not shown.

[0031] Here, the thin film forming section 12 includes a structure in which the in-plane magnetization film 121 and the perpendicular magnetization film 122 are arranged with the non-magnetic body 123 interposed therebetween. That is, the thin film forming section 12 includes a structure in which the in-plane magnetization film 121 and the perpendicular magnetization film 122 are arranged separated by the non-magnetic body 123 with the non-magnetic body 123 sandwiched therebetween. The in-plane magnetization film 121 may be arranged so as to be in contact with the non-magnetic body 123, or another thin film or a gap may be interposed between the in-plane magnetization film 121 and the non-magnetic body 123 as long as the effects of the present disclosure are obtained. Moreover, the perpendicular magnetization film 122 may be arranged so as to be in contact with the non-magnetic body 123, or another thin film or a gap may be interposed between the in-plane magnetization film 121 and the non-magnetic body 123 as long as the effects of the present disclosure are obtained.

[0032] The in-plane magnetization film 121 and the perpendicular magnetization film 122 may be stacked via a non-magnetic material 123 as illustrated in FIG. 1, or may be disposed in-plane on the support layer 11 via a non-magnetic material 123 as illustrated in FIG. 2.

[0033] 1, the thin film forming portion 12 may have an in-plane magnetization film 121 disposed on the support layer 11 side of the non-magnetic body 123 and a perpendicular magnetization film 122 disposed on the opposite side of the non-magnetic body 123 to the support layer 11 side, or, although not shown, may have a perpendicular magnetization film 122 disposed on the support layer 11 side of the non-magnetic body 123 and an in-plane magnetization film 121 disposed on the opposite side of the non-magnetic body 123 to the support layer 11 side. Specifically, FIG. 1 shows an example in which the thin film forming portion 12 includes an in-plane magnetization film 121, a film-like non-magnetic body 123 laminated on the in-plane magnetization film 121, and a perpendicular magnetization film 122 laminated on the non-magnetic body 123.

[0034] In addition, FIG. 1 shows an example in which the in-plane magnetization film 121 is laminated on the support layer 11, but a buffer layer (not shown in FIG. 1) may be formed between the support layer 11 and the in-plane magnetization film 121. In addition, although not shown, when the support layer 11 has the perpendicular magnetization film 122, a buffer layer may be formed between the support layer 11 and the perpendicular magnetization film 122 in the same manner as described above. The buffer layer is formed for the purpose of improving the crystallinity of the thin film laminated above the buffer layer. The buffer layer does not necessarily have to be a single layer, and may be a laminate of multiple layers. In addition, as exemplified in FIG. 2, even when the in-plane magnetization film 121 and the perpendicular magnetization film 122 are arranged in a plane on the support layer 11 via the non-magnetic material 123, a buffer layer can be inserted as appropriate and necessary. In FIG. 2, the reference numeral 125 denotes a buffer layer.

[0035] In addition, the thin film forming portion 12 may have a cap layer 124 formed above a portion where the in-plane magnetization film 121 and the perpendicular magnetization film 122 are stacked with the non-magnetic body 123 interposed therebetween, as illustrated in FIG. 1. Similarly, the thin film forming portion 12 may have a cap layer 124 formed above the in-plane magnetization film 121 and the perpendicular magnetization film 122, as illustrated in FIG. 2. The cap layer 124 is formed for the purpose of suppressing oxidation of the thin film below the cap layer 124. The cap layer 124 does not necessarily have to be a single layer, and may be a laminate of multiple layers. In addition, the cap layer 124 does not necessarily have to be formed on the top layer of the thin film forming portion 12, and one or more other thin film layers may be formed above the cap layer 124 as necessary. 1 specifically shows an example in which the thin film forming portion 12 having a laminated structure in which an in-plane magnetization film 121, a non-magnetic body 123, a perpendicular magnetization film 122, and a cap layer 124 are laminated in this order on the support layer 11. Also, Fig. 2 shows an example in which the thin film forming portion 12 is formed on the support layer 11 such that a portion in which the perpendicular magnetization film 122 and the cap layer 124 are laminated in this order and a portion in which the in-plane magnetization film 121 and the cap layer 124 are laminated in this order are arranged in a plane adjacent to the non-magnetic body 123 via the non-magnetic body 123.

[0036] In the thin film forming section 12, when the perpendicular magnetic film 122 is a multi-layer film, the perpendicular magnetic film 122 can be composed of a multi-layer film in which a lamination unit, in which a second ferromagnetic film 122b different from the first ferromagnetic film 122a is laminated on one side of the first ferromagnetic film 122a, is laminated for one period or more, as illustrated in FIG. 1 and FIG. 2. In this case, the perpendicular magnetic film 122 can have a magnetization direction perpendicular to the in-plane as a whole film by adjusting the thickness of either the first ferromagnetic film 122a or the second ferromagnetic film 122b. In addition, when the perpendicular magnetic film 122 is a multi-layer film, the perpendicular magnetic film 122 can be composed of a multi-layer film having a repeating structure in which ferromagnetic films and non-magnetic films are alternately and repeatedly laminated, although not shown. In this case, the perpendicular magnetic film 122 can have a magnetization direction perpendicular to the in-plane as a whole film by adjusting the thickness of either the ferromagnetic film or the non-magnetic film. In addition, the ferromagnetic film and the non-magnetic film may be stacked alternately and repeatedly so that the ferromagnetic film is positioned on the support layer 11 side, or the non-magnetic film may be stacked alternately and repeatedly so that the non-magnetic film is positioned on the support layer 11 side.

[0037] The thin film forming portion 12 can be formed from a metal material, an insulating material, etc., but from the viewpoint of technical ease of formation on a semiconductor, etc., it is preferable to configure it from a metal material. Furthermore, since the thin film forming portion 12 has electronic conductivity, it can be used in devices that pass electric current. Note that yttrium iron garnet (YIG) is known as a typical material with a small Gilbert damping constant α (α=10 -4 ~10 -5 However, YIG requires special substrates such as gadolinium gallium garnet (GGG) substrates and is difficult to fabricate. Also, YIG is an insulator, so it cannot be used in devices that pass electric current.

[0038] Specific configuration examples of the laminated structure 1 of this embodiment will be described mainly for the case where the perpendicular magnetization film is a multi-layer film or a single-layer film, but the laminated structure 1 of this embodiment is not limited to the following configuration examples. In addition, known documents can be appropriately referred to for the configuration of each film and the magnetization direction of each film.

[0039] -Perpendicular magnetization film 122- (1) When the perpendicular magnetic film 122 is a multilayer film A) [Co / Ni] n In addition, [Co / Ni] n means that the Co film / Ni film stacking unit is stacked for n periods. Also, " / " means that the thin film written to the left of the " / " is on the support layer side, and the thin film written to the right of the " / " is stacked on top of the thin film written to the left (on the opposite side to the support layer side). [Co / Ni] n is [Ni / Co] n The stacking order can be changed as shown below. The same applies below, so the explanation will be omitted. In this case, the first ferromagnetic film 122a in FIG. 1 corresponds to the Co film, and the second ferromagnetic film 122b in FIG. 1 corresponds to the Ni film. Co film thickness: 0.1 nm to 0.5 nm -Thickness of Ni film: 0.3nm to 0.8nm ·Stacking period: 1≦n ·Support layer material: SiO2, Si, Al2O3(0001), MgO(111), Cu Buffer layer: Ta / Pt or Pt / Ta (for example, Ta film 3 nm thick, Pt film 1 nm thick) thickness 20 nm), Pt (e.g., Pt film thickness 3 nm), Ta (for example, Ta film thickness 4.5 nm) B) [Co / Pd] n Co film thickness: 0.2nm to 0.8nm Pd film thickness: 0.4nm to 3.0nm ·Stacking period: 1≦n ·Support layer material: SiO2 Buffer layer: None C) [Co / Pt] n Co film thickness: 0.3 nm to 1.5 nm ·Pt film thickness: 0.4nm to 3.0nm ·Stacking period: 1≦n ·Support layer material: SiO2 Buffer layer: None, Ta (for example, Ta film thickness 4.5 nm) D) [Cu / Ni] n ·Cu film thickness: 4nm to 12nm -Thickness of Ni film: 2nm to 9nm ·Stacking period: 1≦n ·Support layer material: GaAs(001), BaTiO3(001), SrTiO3(001), Si(001) Buffer layer: None, Fe (for example, Fe film thickness 1 nm) E) [FePt / Au] n FePt film thickness: over 0nm, under 1nm ·Au film thickness: over 0nm, under 2nm ·Stacking period: 1≦n ·Support layer material: MgO(111) Buffer layer: None

[0040] (2) When the perpendicular magnetic film 122 is a single-layer film a) Mn 3-x Ga Film thickness: e.g. 60nm ·Support layer material: STO(001), MgO(001) Buffer layer: Pt (e.g., Pt film thickness 5 nm), Cr (e.g., Cr film thickness 5 nm) b) FePt Film thickness: 25nm to 170nm ·Support layer material: MgO(001) Buffer layer: Pt (e.g., Pt film thickness 12 nm), Cr (e.g., Cr film thickness 3nm to 9nm) c)Co 72 Cr 13 Pt 15 Film thickness: e.g. 4nm ·Support layer material: Si(111) Buffer layer: Ti (for example, a Ti film thickness of 5 nm to 10 nm), Ta (for example, Ta film thickness is 5 nm to 10 nm) d) Co 65 Cr 15 Pt 20 Film thickness: e.g. 4nm ·Support layer material: SiO2 Buffer layer: Ru / Ta (for example, Ru film thickness 10 nm, Ta film thickness 5 nm), e)Co 80 Cr 17 Ta3 Film thickness: e.g. 100nm ·Support layer material: SiO2 Buffer layer: None f)Fe Film thickness: e.g. 0.7nm ·Support layer material: MgO(001) Buffer layer: Cr (e.g., Cr film thickness 30 nm) g) Fe 1.5 CoGe Film thickness: 9nm to 80nm ·Support layer material: MgO(001) Buffer layer: TiN (for example, TiN film thickness 30 nm) h) Co2FeSi Film thickness: 0.6nm to 1.0nm ·Support layer material: MgO(001) Buffer layer: Pd or Cr (For example, Pd film thickness 20 nm, Cr film thickness 40 nm) i) Co2FeAl Film thickness: 0.6nm to 1.0nm ·Support layer material: MgO(001) Buffer layer: Pd or Cr (For example, Pd film thickness 20 nm, Cr film thickness 40 nm) j) CoFeB·MgO Film thickness: 0.3nm to 1.0nm ·Support layer material: Si(001) Buffer layer: Ta (for example, Ta film thickness 1.0 nm) k)Co 75 Mn 25 Film thickness: For example, 0.7 nm to 1.0 nm ·Support layer material: SiO2 Buffer layer: MgO (for example, film thickness 2.0 nm) l) FePd Film thickness: 11nm to 17nm ·Support layer material: MgO(001) Buffer layer: Pd (for example, Pd film thickness 50 nm)

[0041] The following are examples of configurations of the in-plane magnetization film 121, the non-magnetic body 123, and the cap layer 124. Note that the following configurations can be combined with the above-mentioned configuration example of the perpendicular magnetization film 122.

[0042] -In-plane magnetized film 121- Examples of the material of the in-plane magnetization film 121 include Fe, Fe alloy, Co, Co alloy, Ni, Ni alloy, etc. Examples of the thickness of the in-plane magnetization film 121 include 0.3 nm or more and 100 nm or less.

[0043] -Nonmagnetic material 123- Examples of the material of the non-magnetic body 123 include Pt, Pt alloy, Ta, Ta alloy, Au, Au alloy, etc. Examples of the thickness of the non-magnetic body 123 include 0.3 nm or more and 20 nm or less.

[0044] -Cap layer 124- Examples of the material of the cap layer 124 include Pt, a Pt alloy, Au, an Au alloy, Ti, a Ti alloy, etc. Examples of the thickness of the cap layer 124 include 1 nm or more and 5 nm or less.

[0045] The laminated structure 1 of the present embodiment described above has the thin film forming portion 12 including a structure in which an in-plane magnetized film 121 whose magnetization direction is in-plane and a perpendicular magnetized film 122 whose magnetization direction is perpendicular to the in-plane are arranged via a non-magnetic body 123. Therefore, according to the laminated structure 1 of the present embodiment, the Gilbert damping constant α can be made small.

[0046] From the viewpoint of power saving of the spintronics device, the Gilbert damping constant α of the laminated structure 1 of the present embodiment is preferably 0.005 (5.0×10 -3 ) or less, more preferably 0.001 (1.0 × 10 -3 ) or less. The smaller the Gilbert damping constant α, the more preferable. -4 ) or more.

[0047] (Spintronics Devices) The spintronics device of this embodiment has the stacked structure 1 of this embodiment. A spintronics device is an electronic device that uses at least one or more phenomena related to spintronics, such as magnetization reversal, spin angular momentum transport, and spin wave transport. Specific examples of spintronics devices include magnetic heads for hard disk drives (HDDs), magnetic devices such as spin transistors, high-frequency devices such as transmitters, and magnetic random access memories. Note that for specific device structures other than the stacked structure, known techniques can be appropriately adopted.

[0048] In the spintronics device of this embodiment described above, the Gilbert damping constant of the multilayer structure 1 of this embodiment is small, so that power consumption can be reduced.

[0049] <Experimental Example> (Preparation of laminated structure samples) Using a molecular beam epitaxy (MBE) device, a 30 nm thick Fe film was grown by MBE on a single crystal MgO (111) substrate at a substrate temperature of 300°C. Next, a 10 nm thick Pt film and a [Co(t nm) / Ni(0.6 nm)]8 multilayer film were grown on the Fe film at room temperature (25°C, omitted below). Next, a 3 nm thick Pt film (cap layer) was formed on the [Co(t nm) / Ni(0.6 nm)]8 multilayer film at room temperature to prevent oxidation. As a result, a stacked structure sample for evaluation was prepared, which has a heterostructure in which Fe film (30 nm) / Pt film (10 nm) / [Co(t nm) / Ni(0.6 nm)]8 multilayer film / Pt film (3 nm) are stacked in sequence on one side of the single crystal MgO (111) substrate of the support layer.

[0050] In addition, [Co(t nm) / Ni(0.6 nm)]8 means that eight periods of stacking units of a Co film with a thickness of t nm / a Ni film with a thickness of 0.6 nm are stacked, and the first period of Co(t nm) is in contact with the Pt film (10 nm). In other words, the notation [Co(t nm) / Ni(0.6 nm)] means that the thin film written on the left side of the " / " is on the support layer side, and the thin film written on the right side of the " / " is stacked on the thin film written on the left side (opposite the support layer side). In this experimental example, the thickness t of the Co film was changed to 0 nm (t = 0), 0.3 nm (t = 0.3), 0.4 nm (t = 0.4), 0.5 nm (t = 0.5), 0.7 nm (t = 0.7), and 0.8 nm (t = 0.8) to prepare each stacked structure sample for evaluation.

[0051] (X-ray diffraction and magnetization measurements of laminated structure samples) The XRD pattern of each laminate structure sample was measured by X-ray diffraction. The magnetization of each laminate structure sample was also measured. The results are shown in Figures 3 to 7. In Figures 3 to 7 (b), IP indicates an in-plane magnetic field, and OP indicates a perpendicular magnetic field.

[0052] As shown in Figure 3(a) (t = 0.3 nm), Figure 4(a) (t = 0.4 nm), Figure 5(a) (t = 0.5 nm), Figure 6(a) (t = 0.7 nm), and Figure 7(a) (t = 0.8 nm), the [Co(t nm) / Ni(0.6 nm)]8 multilayer film has the same crystal structure regardless of the thickness of the Co film. It is also found that it has the same crystal orientation.

[0053] As shown in Fig. 3(b) (t=0.3 nm), Fig. 4(b) (t=0.4 nm), and Fig. 5(b) (t=0.5 nm), the magnetization curves of the multilayered structure samples with [Co(t nm) / Ni(0.6 nm)]8 multilayers with t=0.3 nm, t=0.4 nm, and t=0.5 nm showed a square hysteresis due to the perpendicular magnetic anisotropy of the multilayered film in the low magnetic field region when a perpendicular magnetic field was applied, as shown in Fig. 3(b) (t=0.3 nm), Fig. 4(b) (t=0.4 nm), and Fig. 5(b) (t=0.5 nm). In the heterostructure with t≦0.4 nm, a more clear square hysteresis was observed. In contrast, as shown in Fig. 6(b) (t=0.7 nm) and Fig. 7(b) (t=0.8 nm), the magnetization curves of the multilayered structure samples with [Co(t nm) / Ni(0.6 nm)]8 multilayers with t=0.7 nm and 0.8 nm showed a tendency for the perpendicular magnetic anisotropy to decrease with increasing Co film thickness. These results show that the [Co(t nm) / Ni(0.6 nm)]8 multilayer film becomes a perpendicular magnetization film when t is less than 0.7, and becomes an in-plane magnetization film when t is 0.7≦t or more. It also shows that the magnetization direction can be controlled from perpendicular to in-plane by adjusting t. In the laminated structure sample, the 30 nm thick Fe film is an in-plane magnetization film, and the 10 nm thick Pt film is a non-magnetic film.

[0054] (Evaluation of Gilbert damping constant α) Ferromagnetic resonance (FMR) is characterized by the resonance linewidth ΔH and the resonance frequency f res It is widely used as a powerful tool to estimate the Gilbert damping constant α of a ferromagnetic material from the linear relationship between the two. Therefore, in this experimental example, ferromagnetic resonance measurements (FMR measurements) were performed on each laminate structure sample to calculate the Gilbert damping constant α.

[0055] Specifically, the ferromagnetic resonance measurements were performed at room temperature in the frequency range of 1 to 20 GHz using a vector network analyzer (VNA), as shown in Figure 8. The laminated structure sample was placed on a coplanar waveguide (CPW), and an external magnetic field H ex The measurements were performed by sweeping the microwave frequency applied to the coplanar waveguide while applying a magnetic field H. As shown in Figs. 9 and 10, the ex The resonance absorption spectrum corresponding to each microwave frequency was obtained as a function of the magnetic field H by performing the same procedure for each microwave frequency. In FIG. 10, the curve indicates the resonance line ΔMagS at a resonance frequency of 8.6 GHz. 21 The external magnetic field H ex From this, as shown in FIG. 11, the resonant frequency f res and the resonance linewidth ΔH of the resonance absorption spectrum. As shown in FIG. 11, the value of the resonance linewidth ΔH of the resonance absorption spectrum is res The resonance linewidth ΔH and resonance frequency f of the resonance absorption spectrum are plotted as a function of . res The plot was fitted using the equation to calculate the Gilbert damping constant α.

[0056]

number

[0057] In Equation 2, g is the Lande g-factor, e is the charge of the electron, m0 is the rest mass of the electron, c is the speed of light, and ΔH0 is the frequency-independent broadening of the linewidth due to magnetic inhomogeneity, etc.

[0058] Figure 12 shows the relationship between the resonant frequency f res The relationship between the Co film thickness and the resonance line width ΔH of the resonance absorption spectrum is shown in FIG. 12. In FIG. 12, the Gilbert damping constant α t nm was as follows: α t=0nm =5.61×10 -3 , α t=0.3nm=-3.00×10 -3 , α t=0.4nm =-3.88×10 -3 , α t=0.5nm =-4.30×10 -3 , α t=0.7nm =1.50×10 -2 , α t=0.8nm =3.75×10 -2 .

[0059] As shown in FIG. 12, it can be seen that the Gilbert damping constant α of the laminated structure sample decreases as the thickness of the Co film decreases. Specifically, for example, at t=0.8 nm, ΔH is f res In contrast, for example, at t = 0.5 nm, f res As f increases, ΔH decreases linearly. res It can be seen that the value of α, which indicates the slope in the relationship between ΔH and the magnetization constant, becomes negative. Also, according to Fig. 12, it is estimated that α becomes negative when the thickness t of the Co film is smaller than 0.7 nm, specifically, when it is about 0.6. The physical origin of this anomalous behavior of the negative Gilbert damping constant α has not yet been fully elucidated, but it is thought that the precession of the magnetization of the Fe film occurs due to the interaction between the Fe moment and the perpendicular magnetization film [Co / Ni] n It is suggested that anti-damping may occur through magnetic interactions occurring between the multilayer film. These results show that the Gilbert damping constant α can be reduced by adjusting the value of the thickness t of the Co film. Furthermore, according to the results of this experiment, since a necessary condition for reducing the Gilbert damping constant α is to place the in-plane magnetized film and the perpendicular magnetized film between a nonmagnetic material, it is possible to reduce the Gilbert damping constant α by using in-plane magnetized films other than Fe films, nonmagnetic films other than Pt films, and [Co / Ni] n It can be said that even when a perpendicular magnetization film other than a multilayer film is used, the Gilbert damping constant α can be reduced.

[0060] According to the above results, it was confirmed that a laminated structure with a small Gilbert damping constant α can be obtained by configuring the thin film forming portion formed on one side of the support layer to include a structure in which a perpendicular magnetization film and an in-plane magnetization film are arranged with a non-magnetic material between them. In addition, it can be said that by using this laminated structure in a spintronics device, it is possible to obtain a spintronics device with low power consumption.

[0061] The present invention is not limited to the above-described embodiments and experimental examples, and various modifications are possible without departing from the spirit and scope of the present invention. Furthermore, the configurations shown in the embodiments and experimental examples can be combined in any manner. [Explanation of symbols]

[0062] 1. Laminated structure 11 Support layer 12 Thin film forming section 121 In-plane magnetized film 123 Non-magnetic material

Claims

1. A support layer; A thin film forming portion is formed on one side of the support layer, The thin film forming section includes: a structure in which an in-plane magnetized film, the magnetization direction of which is in-plane, and a perpendicular magnetized film, the magnetization direction of which is perpendicular to the in-plane, are arranged with a non-magnetic material interposed therebetween; Laminated structure.

2. In the thin film forming portion, the in-plane magnetization film and the perpendicular magnetization film are laminated via the non-magnetic material. The laminated structure according to claim 1 .

3. the perpendicular magnetic film is composed of a multilayer film in which a plurality of thin films are stacked, or a single layer film composed of one thin film; The laminated structure according to claim 1 or 2.

4. the perpendicular magnetic film is composed of a multilayer film in which a lamination unit, in which a second ferromagnetic film different from the first ferromagnetic film is laminated on one surface of the first ferromagnetic film, is laminated for one period or more; The laminated structure according to claim 1 or 2.

5. the thickness of either the first ferromagnetic film or the second ferromagnetic film is adjusted so that the magnetization direction of the perpendicular magnetization film is perpendicular to the in-plane direction throughout the film; The laminated structure according to claim 4 .

6. the perpendicular magnetic film has a repeating structure in which ferromagnetic films and non-magnetic films are alternately laminated; The laminated structure according to claim 1 or 2.

7. A spintronics device comprising the laminated structure according to claim 1 or 2.

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